Known techniques for debugging embedded digital processors include the use of on-chip emulation devices whose function is to monitor and control the operation of the digital processor. Such on-chip emulation devices typically have storage capability, and the ability to initiate command and control sequences for the digital processor in response to externally applied signals from a host computer or to detected states of the digital processor.
Communication between the on-chip emulation device (oce) and the host computer is carried out via a link, which is typically a link designed for the particular situation. As a result, signals over the link may be tailored to the particular on-chip emulation device in the interests of efficient debugging.
There is however a problem in that the use of a specialized link dictates a physical link dedicated to the system, and also requires the host computer to be running programs dedicated to the production of signals for the on-chip emulation device of concern.
It is proposed in a copending patent application to provide such a chip with a universal serial bus (usb) port and interface for communication with the on-chip emulator.
It is however desirable to further enhance the communication possibilities to such a chip.